Jenkins 2019 Cluster(1)Version 2.194

Jenkins 2019 Cluster(1)Version 2.194

I install latest version 2.194 war package.

I get this error message in my logging:
2019-09-11 12:51:15.994+0000 [id=45] SEVERE h.i.i.InstallUncaughtExceptionHandler$DefaultUncaughtExceptionHandler#uncaughtException: A thread (Thread-12/45) died unexpectedly due to an uncaught exception, this may leave your Jenkins in a bad way and is usually indicative of a bug in the code.
java.lang.NullPointerException: Cannot invoke method toInteger() on null object
at org.codehaus.groovy.runtime.NullObject.invokeMethod(NullObject.java:91)

Solution:
Currently, I have no idea
https://issues.jenkins-ci.org/browse/JENKINS-52694?page=com.atlassian.jira.plugin.system.issuetabpanels%3Aall-tabpanel

Add Slave Machines
[Manage Jenkins] —> [New Node]
NodeName: centos-dev2

Prepare the slave directory on slave machines
> mkdir ~/tool/jenkins-2.194
> mkdir ~/tool/jenkins-2.194/jenkins-home-slave
> sudo ln -s /home/carl/tool/jenkins-2.194 /opt/jenkins-2.194

> sudo ln -s /opt/jenkins-2.194 /opt/jenkins

Remote root directory  /opt/jenkins/jenkins-home-slave
Host: centos-dev2
Credentials: I use root and use private key to ssh to the slave
Host Key Verification Strategy: Non verifying Verification Strategy

Save and we will have one slave.

I notice there is a warning message
centos7 clock difference

Solution:
https://www.tecmint.com/set-accurate-server-time-in-centos/

> sudo yum install ntp ntpdate
> sudo systemctl start ntpd
> sudo systemctl status ntpd

> sudo systemctl enable ntpd

References:
https://issues.jenkins-ci.org/browse/JENKINS-52694?page=com.atlassian.jira.plugin.system.issuetabpanels%3Aall-tabpanel